Reynolds Number Impact on High Pressure Turbine Flows

Abstract During operation, turbine blades in aircraft engines can experience flows over a wide range of Reynolds numbers. This range is impacted by engines of different sizes, as well as different operating altitudes, all of which add to the overall range of Reynolds numbers that are relevant for aircraft engine design. Unfortunately, increasing flow Reynolds number has a significant impact on the mesh resolution required for accurately simulating wall-resolved LES models due to the mesh resolution required to capture the near-wall flow physics. During the design process, providing engineers a detailed understanding of the flow physics phenomena, and how they change with Reynolds number, could lead to more efficient and durable turbine designs. In this paper we present the study of flows around an uncooled high-pressure turbine blade. The simulations are completed with the high-order GENESIS code, which has been successfully applied to thread-parallel compute architectures, such as large computational systems with GPU capability. The simulations cover a range of Reynolds numbers in order to study the impact of Reynolds number increase over a fixed geometry. This allows for examining the impact on flow physics of interest, such as boundary layer evolution, laminar-to-turbulent transition, and wake shedding. The numerical results show that as Reynolds number is increased, a critical value is reached where the shedding behavior of trailing edge vortices changes, resulting in a jump in wake loss. Examination of the local flowfield quantities demonstrates that this change is due to a shift from laminar to turbulent flow on both sides of the airfoil, contributing to destabilization of the shear layer, resulting in larger vortices being shed.